One of the most prevalent manifestations of primary antibody deficiencies is gastrointestinal disorders. In this study we reviewed 83 patients including 25 with X-Linked agammaglobulinemia, 40 with common variable immunodeficiency, 14 with IgA deficiency and 4 with IgG subclass deficiency. The mean age of patients was 10 year (1-28 years). The ratio of male to female was 1.5. Gastrointestinal system was affected in more than half (57.8%) of them. The most common symptom was diarrhea (56.6%) and the most prevalent pathogen was. G. Lamblia. Other disorders were chronic active hepatitis in 6 patients, ulcerative colitis in 2, small intestinal villus atrophy in 5, nodular lymphoid hyperplasia of small intestine in 3 and chronic gastritis in 4 patients. One patient suffered from abdominal lymphoma. We found a direct correlation between failure of patients to thrive and the duration of the delay in diagnosing the underlying disease. This difference was more apparent in those with both antibody deficiency and gastrointestinal involvement.